An Arabi entered the mosque, prayed two rak'ahs, then said, "Allah, have mercy on me and on Muhammad, and do not show mercy to anyone else along with us."The Messenger of Allah ﷺ said, "You have restricted something vast."
أخبرنا عبد الله بن محمد بن عبد الرحمن الزهري قال حدثنا سفيان قال أحفظه من الزهري قال أخبرني سعيد
أن أعرابيا دخل المسجد فصلى ركعتين ثم قال اللهم ارحمني ومحمدا ولا ترحم معنا أحدا فقال رسول الله ﷺ لقد تحجرت واسعا
[Its isnad is sahih] Abu Dawud narrated it in the Book of Purification, chapter on land struck by urine, hadith 380, and Tirmidhi in the Book of Purification, chapter on what has been said about urine striking the ground, hadith 147, from the hadith of Sufyan bin Uyayna through this route, and Tirmidhi said, hasan sahih, and it is in Al-Kubra, hadith 555, and Ibn Jarud graded it sahih, hadith 141, along with others.Saeed here is Ibn Musayab.